JPH034502Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to an injection mold, and more specifically, to a mold that performs gate cutting while the mold is in a closed state.

(Prior Art) As a method of gate cutting in injection molding, an injection mold is provided with a slide core having a runner gate and an actuating cylinder connected to the slide core, and after injection molding, the mold is left in a closed state. It has been proposed to perform gate cutting by sliding the slide core (see Japanese Patent Laid-Open No. 19127/1983).

This method has the advantage that the cut surface is clean compared to other methods in which gate cutting is performed when opening the mold.

(Problems to be Solved by the Invention) However, since the slide core is slid while the mold remains closed, the load on the operating cylinder is heavy.

In particular, in order to minimize burrs that occur between the mold and the slide core, the slide core must be placed in close contact with the mold, which increases the initial resistance of the slide core. , malfunction of the operating cylinder is likely to occur. In addition, there is also the problem that the operating cylinder becomes larger.

The present invention was developed in consideration of the above problems, and its purpose is to minimize the initial resistance of the slide core even if the slide core is placed in close contact with the mold to reduce the occurrence of burrs. An object of the present invention is to provide a mold for injection molding.

(Means and effects for solving the problem) In order to achieve the above-mentioned descriptive problem, in the present invention, the slide core has a first core connected to an actuating cylinder, and a first core having a runner gate. 2
The first structural feature is that the second core is divided into two cores, and the second feature is that the second core is integrated with the first core and slides after the initial stroke of the operating cylinder. The reason is that it is a driven core. Thereby, during the initial stroke of the working cylinder, only the first core is slid by the working cylinder. In addition, a third feature is that the first core has a function of bringing the mold and the driven core having the runner gate into close contact with each other by a wedge action, and that the first core has the function of bringing the die and the driven core having the runner gate into close contact with each other, and that action is performed during the initial stroke of the operating cylinder. The reason is that I decided to remove it.

Specifically, assuming an injection mold in which a slide core having a runner gate is slid by an operating cylinder to perform gate cutting while the mold is in a closed state, the slide core is connected to the operating cylinder. It has a divided structure of a wedge core and a driven core having the runner gate, and the wedge core is in sliding contact with a surface of the driven core opposite to the surface on which the runner gate is provided, and the wedge core is in sliding contact with the surface of the driven core opposite to the surface on which the runner gate is provided. The driven core has a wedge shape that releases the pressing force on the driven core at the initial stroke of the cylinder, and the driven core has a first groove formed on the wedge core after the initial stroke of the working cylinder.
a second engaging part that engages with the engaging part of the second engaging part;
The wedge core is configured to slide integrally with the wedge core after the initial stroke of the actuating cylinder.

With this configuration, the conflicting demands of the need to have the slide core tightly adhered to the mold in order to reduce the occurrence of burrs and the need to reduce the initial resistance of the slide core during gate cutting are satisfied. The Rukoto.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

In the figure, reference numeral 1 denotes an injection mold device according to the embodiment, and the injection mold device 1 has a fixed die 3 fixed to a main body 2 and can be moved into and out of contact with the fixed die 3. A gate cutting means 5 attached to a split mold A consisting of a movable die 4 is provided, and the split mold A
In this case, a cavity 6 is formed between the fixed die 2 and the movable die 3 when the mold is closed.

The molten resin discharged from the spool 7 of the injection molding machine passes through the runner gate 8 and the gate 9 leading to the cavity 6, is filled into the cavity 6, and is then hardened to mold a predetermined resin product B. . Here, the resin product B is an automobile bumper. The automobile bumper B thus formed is subjected to a process of gate cutting and mold opening by gate cutting means 5, which will be described in detail later.
Knockout pin 10 protruding into cavity 6
The mold is released by

The gate cutting means 5 is provided in the main body 2 facing the split mold A, and its schematic structure is as follows.
It consists of a slide core 11 and an operating cylinder 12 that slides the slide core 11 in sliding contact with the split mold A. The slide core 11 has a divided structure including a driven core 13 facing the split die A and a wedge core 14 disposed on the back side thereof.

The driven core 13 has a runner gate 8 formed on its front face facing the split die A, and a stepped part 13a formed on its back face, with a two-step stepped structure having a convex part 13b at the lower part. It is said to be a face.

Three wedge cores 14 are arranged in parallel at intervals in the longitudinal direction of the driven core 13.
4 are connected to cylinder rods 15a of the working cylinder 15, respectively. The wedge core 14 has a surface facing the driven core 13 that is connected to the upper stage portion 14.
A and the lower part 14b form a three-step stepped surface, and the part above the lower part 14b is adapted to be able to come into sliding contact with the driven core 13, and has the same length as the driven core 13. . And wedge core 14
The distance L ₁ between the upper stage part 14b and the lower stage part 14b is
It is set slightly longer than the convex portion 13b (L ₂ ) of the driven core 13 (L ₁ >L ₂ ).

Further, on the back side of the wedge core 14, there is a tapered surface 16 that gradually approaches the front side toward the upper end.
Corresponding to this tapered surface 16, a main body side tapered surface 17 is formed on the main body 2 by a block 18.

The stroke of the actuating cylinder 12 is regulated by the engagement of limit switches 22, 23 by two spaced apart protrusions 20, 21 on the rod 19 depending from the wedge core 14.
In addition, in the figure, the reference numeral 24 is a stopper provided integrally with the wedge core 14, in FIGS. 2 and 3, the reference numeral 25 is a cooling pipe, and the reference numeral 26 is an ejector pin for discharging the hardened resin at the runner gate. The ejector pins 26, 26 are adapted to move up and down together with the slide core 11.

Next, the operation of the gate cutting means 5 in the gate cutting process will be explained based on FIGS. 4 to 6.

FIG. 4 shows a state in which the filling of the resin into the cavity 6 is completed. In this state, the driven core 13 and the wedge core 11 are at the upper end position, and the driven core 1
3 is pressed by the wedge core 14 and brought into close contact with the split die A, thereby preventing the occurrence of burrs between the driven core 13 and the split die A.

After the resin in the cavity 6, especially the runner gate 8, has hardened, the actuation cylinder 12 is operated while the fixed die 3 and movable die 4 remain closed.

At the initial stroke of the cylinder rod 12a,
Only the wedge core 14 slides in response to the shortening movement of the cylinder rod 12a. As the wedge core 14 slides, its tapered surface 16 separates from the main body 2 (main body side tapered surface 17), and the wedge action by the wedge core 14 is released. As a result, driven core 1
The pressing force on 3 is released.

Then, when the upper step 14a of the wedge core 14 engages with the step 13a of the driven core 13 (see FIG. 5), the driven core 13 is integrated with the wedge core 14,
Both slide in response to the shortening movement of the cylinder rod 12a. And this driven core 13
Gate cutting is performed by the slide (see Fig. 6).

In this way, during the initial stroke of the actuating cylinder 12, only the wedge core 14 slides, and since the wedge action is immediately released when the wedge core 14 starts sliding, the actuating cylinder 12 receives almost no initial resistance. It will work. Therefore, there is no fear that the operating cylinder 12 will malfunction, and the operating cylinder can be sufficiently small.

(Effects of the invention) As is clear from the above explanation, according to the invention, even if the slide core and the mold are placed closely together, the initial resistance to the actuating cylinder is small due to the action of the wedge core. Therefore, there is no fear of malfunction of the working cylinder, and there is an advantage that the working cylinder can be made smaller, so it has high practical value.

[Brief explanation of the drawing]

Fig. 1 shows the main parts of the embodiment, Fig. 2 is a sectional view, Fig. 2 is a front view of the gate cut means attached to the embodiment, and Fig. 3 is a sectional view as shown in Fig. 2. 4 to 6 show each process of gate cutting. FIG. 4 is a process diagram showing before the start of the gate cutting process, FIG. 5 is a process diagram showing immediately before gate cutting, and FIG. 6 is a process diagram showing the end of gate cutting. 1: Injection mold device, 3: Fixed die, 4:
Movable die, 5: Gate cutting means, 6: Cavity, 8: Runner gate, 9: Gate, 11: Slide core, 12: Operating cylinder, 13: Driven core, 13a: Step part (second (engaging portion), 14: wedge core, 14a: upper stage portion (first engaging portion) provided in the wedge core, 14
b: Lower stage portion provided on the wedge core, 16: Tapered surface provided on the wedge core.

Claims (1)

[Claims for Utility Model Registration] An injection mold in which a slide core having a runner gate is slid by an operating cylinder to perform gate cutting while the mold is in a closed state, wherein the slide core is connected to the operating cylinder. and a driven core having the runner gate; the wedge core is in sliding contact with a surface of the driven core opposite to the surface on which the runner gate is provided; The driven core has a wedge shape that releases the pressing force on the driven core at the initial stroke of the working cylinder, and the driven core has a first groove formed on the wedge core after the initial stroke of the working cylinder.
a second engaging part that engages with the engaging part of the second engaging part;
An injection molding mold, characterized in that the mold is adapted to slide integrally with the wedge core after the initial stroke of the working cylinder.